Home › Browse Calibers › .30-378 Wby. Mag.
Common uses: Hunting, Big Game, Long Range
| Type | rifle (centerfire) |
| Typical load | 180gr Hornady Custom GMX |
| Muzzle velocity | 3190 fps |
| Muzzle energy | 4068 ft-lb |
| Published G1 ballistic coefficient | 0.485 |
| Case length | 74 mm |
| Overall length | 94 mm |
| SAAMI max pressure | 65000 PSI |
| Range (yd) | Velocity (fps) | Energy (ft-lb) | Drop (in) |
|---|---|---|---|
| 0 | 3190 | 4066 | -1.5 |
| 100 | 2982 | 3553 | 0 |
| 200 | 2784 | 3098 | -2.4 |
| 300 | 2594 | 2690 | -9.4 |
| 400 | 2413 | 2327 | -21.4 |
| 500 | 2239 | 2003 | -39.5 |
At 1,000 yards, .30-378 Wby. Mag. (180gr at 3190 fps, 100 yd zero, standard conditions) has a modeled come-up of about 25.0 MOA / 7.3 MIL, retaining 1486 fps (supersonic).
| Range (yd) | Velocity (fps) | State | Drop (in) | Elev (MOA) | Elev (MIL) |
|---|---|---|---|---|---|
| 300 | 2594 | Supersonic | -9.4 | 3.0 | 0.87 |
| 400 | 2413 | Supersonic | -21.4 | 5.1 | 1.49 |
| 500 | 2239 | Supersonic | -39.5 | 7.6 | 2.20 |
| 600 | 2072 | Supersonic | -64.5 | 10.3 | 2.99 |
| 700 | 1912 | Supersonic | -97.7 | 13.3 | 3.88 |
| 800 | 1761 | Supersonic | -140.4 | 16.8 | 4.87 |
| 900 | 1618 | Supersonic | -194.2 | 20.6 | 5.99 |
| 1000 | 1486 | Supersonic | -261.4 | 25.0 | 7.26 |
Extended predictions beyond 500 yards are modeled from the same G1 engine — useful for initial DOPE, but outside the 500-yard manufacturer-table validation audit. Confirm with observed DOPE, especially near transonic.
A retained-energy reference only — not a shoot/don't-shoot distance. Real effective range depends on your accuracy, shot placement, bullet construction, and conditions. The ~1,000 ft-lb (deer-sized) and ~1,500 ft-lb (elk-sized) figures are commonly cited rules of thumb, not standards.
Your barrel, ammunition lot, and conditions will differ — always verify against the manufacturer's data and your own rifle.
This is an overbore magnum built for maximum reach, pushing standard .30-caliber hunting bullets to velocities well beyond conventional magnums and delivering a very flat trajectory with high retained energy at long distance. Hunters use it on open-country big game where shots can stretch far and where its energy and wind-bucking speed are genuine advantages on elk-sized and larger animals. Those gains come at a steep cost: it consumes a huge charge of slow-burning powder, generates heavy recoil and muzzle blast, and is notorious for eroding barrel throats quickly, so a barrel's accurate life is short compared with ordinary cartridges. It is best understood as a specialist's long-range and big-game round rather than an everyday hunting choice, rewarding shooters who want extreme performance and are willing to accept the recoil, expense, and barrel wear that come with it.
The .30-378 Weatherby Magnum traces to a 1959 U.S. Army request (from Redstone Arsenal) for a cartridge capable of driving light projectiles at extreme velocity to test their effect on armor, work that led Roy Weatherby to neck the massive .378 Weatherby Magnum case down to .30 caliber. Weatherby kept the round as a proprietary wildcat for decades before introducing it as a standardized factory chambering in the Mark V rifle in 1996, with Norma Precision providing the loaded ammunition. It retains the belted case and double-radius shoulder of its .378 parent and its enormous powder capacity, and it earned a reputation as one of the flattest-shooting and highest-velocity .30-caliber production cartridges ever offered.
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